1. Field of the Invention
The present invention relates to an adjustable deadlatch. Specifically, the invention relates to a deadlatch which is adjustable between a 23/8" and a 23/4" backset.
2. Description of the Prior Art Entry doors are typically made to accept deadlatch locks having backsets of either one of two sizes. The normal wooden household door typically uses a deadlatch lock having a backset of 23/8". Heavy duty metal doors which may be used for commercial or industrial purposes, or may be used for residential purposes, typically has the deadlatch having a backset of 23/4". These metal doors are normally sold with a premade opening for a 23/4" backset for the latch.
In the past, separate deadlatches were used depending upon the particular backset. Specifically, if the door requires a deadlatch having a 23/8" backset, a deadlatch having this dimension was used with the lock. On the other hand, if the door required a deadlatch with a 23/4" backset, this size deadlatch was provided even though the remaining portions of a lockset might be identical to lockset used with the 23/8" backset latch. In other words, the only difference between the locks for use with either the 23/4" or 23/8" backsets was the deadlatch itself.
It has, therefore, been considered desirable to provide for an adjustable deadlatch that can be used with either a 23/8" or 23/4" backset. This would eliminate the cost of manufacturing two separate deadlatches and would also eliminate the necessity of stocking a double inventory for complete locksets or for deadlatches. An adjustable deadlatch could, therefore, greatly simplify the inventory requirement and thereby reduce the costs of stocking this double inventory.
Unfortunately, a number of the adjustable deadlatches provided by the prior art have been complicated in structure and cumbersome in operation. For example, one such structure includes a number of arm members which must be pivoted out of the way such as a pin member extending outwardly from the deadlatch. The pin member is then pushed to translate a portion of the latch structure between the 23/4" and 23/8" backset positions. The arm members must then be pivoted back to lock the deadlatch in position. Other prior art devices include removable pieces which must be extracted and repositioned or removed completely and all of these prior art devices do not provide for a simple reliable and easily operated adjustable deadlatch.
In order to overcome some of the described difficulties, an approved adjustable deadlatch is shown in U.S. Pat. No. 4,759,576 issued July 26, 1988 which provides for an adjustable deadlatch which is simpler in structure, but which requires a three step procedure in order to provide for the adjustment between the backset positions. Specifically, in U.S. Pat. No. 4,759,576, the backset adjustment from a first position to a second position is provided by a first step of rotating cylindrical members in a first direction to release a detent. In a second step the cylindrical members are moved logitudinally relative to each other to adjust the backset position from the first position to the second position. The final step is a rotation the cylindrical members in a second direction opposite to the first direction to lock the deadlatch in the second backset position. The present invention provides for a simpler adjustment structure than that shown in U.S. Pat. No. 4,759,576.